Electrically driven portable bag sewing machine



April 12, 1960 F. LUTZ ETAL 2,932,256

ELECTRICALLY DRIVEN PORTABLE BAG SEWING MACHINE Filed July 15, 1957 4Sheets-Sheet 1 FIG.|

April 1960 F. LUTZ arm. 2,932,266

ELECTRICALLY DRIVEN PORTABLE BAG SEWING MACHINE Filed July 15. 1957 4Sheets-Sheet 2 FIG. 2

April 12, 1960 F. LUTZ ETAI.

ELECTRICALLY DRIVEN PORTABLE BAG SEWING MACHINE Filed July 15. 1957 4Sheets-Sheet 3 April 12, 1960 F. LUTZ ETAL 2,932,266

ELECTRICALLY DRIVEN PORTABLE BAG SEWING MACHINEv Filed July 15, 1957 4Sheets-Sheet 4 FIG.5

Unite ELECTRlCA'LLY DRIVEN PORTABLE BAG SEWING MACHINE Friedrich Lutz,Stuttgart-Degerlock, and Herman Daniel,

Stuttgart, Germany, assignors to Union Special Maschinenfabrik,G.m.b.H., Stuttgart, Germany This invention relates to electricallydriven portable bag sewing machines of the character adapted to be heldin the hand of the operator and guided by such hand across the tops offilled bags for closing the same.

An object of the invention has been to facilitate the manipulation ofthe sewing machine during its operation. Toward this end novel means areprovided for energizing and deenergizing the electric motor which isconnected with the sewing machine for driving the same. The necessityfor operation of a switch by the hand or a finger or thumb of theoperator to connect and disconnect the driving motorfrom a power sourcehas been eliminated. Means are provided for automatically closing andopening a switch, for the purpose indicated, by the action of the work,such as the tops of filled bags, in the course of their movementrelative to the stitch forming, work feeding and other Operating devicesof the machine.

Heretofore the operation of portable electrically driven bag sewingmachines has been controlled by the hand of the operator, usually by thethumb of the hand holding the unit, and for this purpose an electricswitch has been provided on or adjacent the handle of the sewingmachine. With this arrangement it has been necessary to hold the switchin its on position by the hand or thumb as long as it is desired tomaintain the machine in operation. As a result, the hand of the operatorhas become fatigued at more frequent intervals than is desirable.Moreover, experience has shown that, depending upon the skill of theoperator, the switch has been operated to cause driving of the motor andthe sewing machine for varying lengths of time before it has beennecessary or desirable and the motor has been disconnected from thepower source for varying periods after it has been necessary ordesirable to have the machine in operation. This has resulted in theformation of excessively long chains of thread both in advance of andfollowing the actual stitching of the bag closure itself, with attendantthread wastage.

In accordance with the present invention, the connection anddisconnection of the driving motor with the power source does not dependupon the skill of the operator. A feeler member provided on the sewingmachine in the path of the relative movement between the machine and thework being stitched is arranged to be acted upon by the work as itapproaches the stitching point and this feeler member is permitted toreturn to normal after the work has passed an appropriate distancebeyond the stitch forming point. This results in the oonsumption of onlythe desired amount of thread in performing the stitching operation, suchas the closing of filled bags. Moreover, the operator is no longercalled upon to use his hand or a finger or thumb to depress a switchbutton continuously during the seaming operation. Thus fatigue of theoperator is minimized and the operator is able to direct' his attentionexclu-' sivelyto the correct guiding of the sewing machine across ratesPatent the top of the filled bag. The arrangement is such that thelifting of the feeler switch which controls the delivery of current tothe drivng motor and the latter remains in operation until the work haspassed through the stitch forming zone of the machine and a suitableamount of thread chain has been formed and cut.

The feeler member in accordance with the invention is of elongated formand extends in a direction parallel to the direction of sewing,preferably outwardly of the surface of the throat plate which serves tosupport the work, such as the pinched together walls at the top of afilled bag, during the relative movement between the machine and thework. A special feature of the feeler member is the provision of alongitudinally extending recess in the work engaging face thereof. Thework engaging portion of the member is thus of channel form or U-shapedin cross-section and the legs of the U, when no work is present, areadapted to pass through parallel elongated openings or slots in thethroat plate of the machine. The arrangement is such that the memberengages the work, which passes between it and thethroat plate, along tworelatively long but narrow strips while theintermediate portion of thework between these strips and the portions at the opposite sides thereofare well supported by the throat plate. This makes possible the properactuation of the feeler member by relatively soft and thin material suchas involved in onion bags, small linen bags and the like which may bestitched by the machine; Such soft and thin material will resist beingdepressed into the elongated narrow slots in the throat plate in' viewof the support of the material between the two slots and at the twosides thereof. This is in spite of the fact that the feeler member isurged by a spring action, preferably a relatively light one, in adirection to carry the legs of the U into the elongated slots oropenings in the throat plate. It will be apparent that if the feelermember serves to force the thin material into the elongated openings ofthe throat plate, the switch mentioned above would be shifted to or leftin its open position and the motor would stop.

Another feature of the invention is the mounting of the feeler member atthe free end of one arm of a twoarmed lever, the latter being mounted toswing about the same axis as the needle lever of the sewing machine.Adjacent its pivot point the lever is provided with a transverselyextending portion of generally U-shaped configuration which provides twolaterally spaced pivot points, along the same axis, for the lever as'awhole. Aligned pivot pins provide for mounting of the lever on a hollowshaft about which the needle lever is rocked. Thus, a very simple,compact and reliable mounting for the feeler member is provided. Thesecond arm of the lever mentioned is provided with -a spring urged pinor plunger adjacent its outer end arranged to cooperate with anoutwardly spring urged plunger or button of a quick action switch. Thearrangement is such that when the feeler member is raised or forced awayfrom the throat plate by the work the spring urged pin carried by thelever willdepress the switch button to close the circuit to the motor.If the feeler'member is raised or shifted to a greater extent thanrequired to move the switch button through its full travel the springurged pin carried by the leverwill be shifted in relation to the latterto compress the spring. When the work being stitched has passed beyondthe feeler member, the latter returns to its normal position under the,actiOn, of the two springs mentioned. That acting on the switchbutton-is the one whi h need o be o r o e in c o gcircuit to the moto bythe action of the, work. H

A further feature of the invention is the formation of the forward endof the feeler member in a U-shape. Th ser es; sa guar f rthefi g rs ofthe ope ator to member operates an electric prevent accidental contactwith the stitch forming devices and top feed mechanism upon introducingthe work into the machine. It is arranged to surround the outer or topfeed dog and the free end of the presser foot of the machine and thusforms a guard around these. Also, the U-shaped portion of the feeler mayat times be grasped 'by theoperator to lift the feeler member and thusrock its carrying lever to close the switch and bring about operation ofthe motor. This may be done when it is found that the material beingstitched has too little strength orstiffness to raise the feeler memberitself.

A special feature is the arrangement by which the lever that carries thefeeler member is connected with the switch only by contact between theplunger on the lever with the push button of the switch. Moreover, theswitch and its electrical connections with the motor are .all carried bythe latter. In this way the motor may be disconnected from the sewingmachine without disturbing the electrical connections to the drivingmotor. V Other objects, features and advantages of the invention willappear from the detailed description of an illustrative embodiment ofthe invention which will now be given in conjunction with theaccompanying drawings in which:

Fig. 1 is a side elevational view of the sewing machine as seen from theside from which the work leaves the machine;

Fig. 2 is an end elevational view of the machine as seen from the rightin Fig. 1, the thread supply spools or cones being omitted; 1

Fig. 3 is a bottom view of the right hand portion of the machine asshown in Fig. 1; V Fig. 4 is a view similar to Fig. 1 but showsschematically the electric-a1 circuit for delivering current to thedriving motor; and I i Fig. 5 is a side elevational view of a portion ofthe machine as seen from the opposite side from that illustrated inFigs. 1 and 4.

The improved control mechanism of the present invention has been shownas applied to an electrically driven portable bag sewing machine of thecharacter fully disclosed in applicants pending application Serial No.535,- 316, filed September 20, 1955. Since the present invention is notconcerned with the details of the construction 1.0f the machine itself,these are shown to only a limited extent in the present case. Referenceshould be had to the pending application for a fuller disclosure ofsuitable stitch forming, work feeding and thread chain cuttingmechanism.

As shown, the sewing unit comprises a motor 1 which is connected with asewing machine 2 directly through a flange 3 of the motor housing. Abayonet type connection may suitably be provided between the motorflange 3 and the machine, as disclosed in said pending application. Thiscomprises hexagonal head screws 3a, only one being shown in Fig. 5,extending from the machine frame and arranged to cooperate with keyslots 3b in the flange with the heads of the screws extending intorecesses 3c and 3d in the flange. As also disclosed therein, the rotaryshaft of the motor is connectable with and disconnectable from drivenparts within the sewing machine by mere application and removal of themotor. To the top of the motor housing there is secured a carryinghandle 4 by which the entire unit may be carried and by which the sewingmachine may be guided across the work during the sewing operation. Inthe top of the handle, adjacent the forward end thereof, is theoperating button of a switch 5, which button is adapted to be depressedto close the switch. It is illustrated in depressed position in Fig. 1and is being held in such position by a spring detent or clip 6 which,upon depression of the push button, rides over a shoulder at the forwardendof the button to retain the same flush with the top of the handle.When the machine is in use the switch 5 is retained continuously in itsclosed position by the spring element '6. Should it become necessary,however, to stop the plate.

machine in the course of a seaming operation, the operator may releasethe push button 5 by simply pressing the spring latch 6 forwardly by afinger or thumb. A spring embodied in the switch 5 will at this timelift the push button and open the switch.

The sewing machine is adapted to produce a double chain stitch and isprovided for this purpose with a curved needle 7 and a thread carryinglooper 8 which are shown in Figs. 1, 3 and 5. The curved needle 7 ismounted in a socket in the lower end of a needle lever 9 which isarranged for rocking movement about the axis of a hollow shaft 10 (Figs.1, 2 and 3). A two-armed lever 11 having arms 11a and 11b is alsopivotally mounted for rocking movement about the axis of the shaft 10.At the lower end of the arm 11a of the lever, which is substantiallylonger than the arm 11b thereof, there is mounted a feeler member 12,this being secured to the lever by screws or the like as shown inFig. 1. Feeler member 12 is urged against a throat plate 13 of thesewing machine and is arranged to be engaged by the work, such as thepinched together tops of filled bags, as the machine is moved intoengagement with such work to effect a seaming operation. The arrangementis such that the feeler member is urged by the work away from the throatplate 13 thus swinging the lever 11 about its pivot 10. This, by theconnections to be described, will serve to close a second switch, whichis in series with the switch 5, in the circuit from a power source tothe driving motor 1. Peeler member 12 has its main portion extendingparallel with the line of stitch .formation and is elongated in thisdirection to an extent sufiicient to insure its maintenance of theswitch, which it controls, in closed position from a time slightlybefore the Work reaches the stitch forming point until a suitable 'timeafter the trailing end of the work passes beyond the stitch formingpoint. That portion of the feeler member which cooperates with the workis of channel form,

a long, narrow section 13b of the throat plate which lends support tothe work during the relative movement between the work and the throatplate. By virtue of this construction the danger of forcing relativelylight or thin material into the openings in the throat plate, by theaction of the feeler member, is minimized; This insures proper action inthe seaming of most types of bags. The relatively thin and flexiblematerial of onion bags and the like is capable of forcing the feelermember away from the throat plate and retaining the same with the ribsthereof out of cooperation with the slots 13a in the throat It will benoted in this connection that the material being stitched is supportedby portions of the throat plate above and below the slots 1311 as wellas by the strip extending longitudinally between these slots.

At its forward end the feeler member 12 is' bent upwardly andrearwardly, as indicated at 1212 in Fig. 2, to provide a U-shapedconfiguration. This portion of the feeler member, moreover, as shownin'Fig. 3, is curved outwardly away from the throat plate 13. It servesthe dual purpose of providing a guard to prevent the hand of theoperator from coming into the region of the curved needle, the presserfoot and the top or outer work feeding members and of also providing ameans for lifting the feeler member in the event that this should becomenecessary due to the failure of especially thin, lightweight material toforce it outwardly as the machine is moved relative to the Work. The"operator may simply force the portion 12b away from fthe'throat plateby means of the hand which assists in guiding the work' in relation, tothe sewing machine, thereby rocking the lever 11 and closing the switchin the circuit to the motor.

The lever 11 has, adjacent its pivot, a substantially U-shaped,laterally extending portion 14 (Figs. 1, 2 and 3). This portion of thelever extends around the housing 2 and enables the mounting of the leveron the shaft 16) by means of conically pointed pivot elements 15 and 16adapted to enter the ends of the axially extending bore of the shaft.The element 15 is preferably screw threaded into the lever 11 and isprovided with a lock nut for holding it in set position. This enablesadjustment of the pivot 15 to provide the desired free swinging actionof the lever while maintaining it against any appreciable lateral orwobbling movement. Also, the screw element 15 may be removed or loosenedsuf ficiently to enable the entire lever structure to be removed fromand applied to the machine. Pivot 16 may suitably be riveted to theother arm of extensionld.

In a socket at the free end of the arm 11b of the lever there is mounteda pin or plunger 17 whichis urged downwardly by a spring 18. The spring13 normally urges the plunger 17 into the position shown in Figs. 1 and4. A cross pin 17a in the plunger serves to prevent further downwardmovement thereof. At its free end the plunger 17 engages a button orplunger 19 of an electric switch 2% of any suitable construction,preferably of the quick action type which closes the switch quickly.upon a predetermined inward movement of the button 19. When this switchis closed and the switch 5 is also closed, a circuit is completed fromline E extending from a suitable source of power to the motor 1 (Fig.4). It will be noted from Figs. 1 and 4 that when the feeler member 12is urged toward the right by the action of the work passing between thefeeler and the throat Plate 13, the lever 11 will be rocked in acounterclockwise direction to bring about depression of the button 19 toclose the switch 29. if the lever 11 is given a greater movement thanthat permitted by the pin 19,.the plunger 17 will remain stationary andthe lever will simply compress the spring 18 to allow for the extramovement.

.This may occur, for example, when thick materials are tion by thespring acting on the button or plunger 19 of the switch This will causeopening of the switch. If the spring 18 has been compressed due to thethickness of the work, this will also participate in the clock wisemovement of the lever 11. Spring 18 is somewhat stiffer than thatserving to force the button 19 outwardly so that the latter will becompressed first in the course of actuating the switch.

Switch 26 is connected with the handle 4 of the machine. For thispurpose a bracket 20a is secured to the bottom of the handle and isprovided with a downwardly extending portion'at its free end to whichthe switch is secured. This arrangement is'such that if the motor 1 isdetached from the sewing machine 2, the switch 24} will remain rigidlyconnected with the motor since'the handle 4 is attached to. the latter.Thus, none of the electrical connections are disturbed in detaching themotor from the machine. As explained, the only connection between thelever 11,carried by the sewing machine, and the switch 20 is the contactbetween the p u g 17 d he butto 5 ch W interfere with the detachment ofthe motor. In this way it is insured that no improper connection of theelectrical circuits will take place upon the detachment and reconnectionof the motor with respect to the sewing machine.

The length of the feeler member 12 is determined in accordance with therequirements for the specific purpose of the machine. In any case it isdesirable to start the motor and to maintain it and the machine inoperation from a time slightly before the bag reaches the stitch formingpoint until a sufiicient time after the bag has as d h s it h form n ntso tha a ch in o suitable length is produced by the stitch formingdevices beyond the trailing end of the work to enable the chain cuttingdevices provided on the machine to be made effective to sever the freechain. As explained in the above-mentioned pendim application, the chaincutting device is operatedso long as the machine is in operation, but itis not effective to sever the chain until the bag or other work isshifted laterally relative to the machine to a certain extent.

Referring again to Fig. 4, it will be seen that in the normal use of theunit the switch 5 will be held closed by the spring clip or detent 6 butno current will be delivered to the motor until the switch 20 is closedby the swinging of the lever 11 under control of the member 12. ifduring the sewing operation anything should develop which makes itnecessary to immediately stop the motor 1, while the work is stillholding the switch 20 in closed position, the operator may simply s hiftthe spring latch 6 with his thumb into releasing position to permit theswitch 5 to open under the action of its own spring. This willimmediately open the circuit from the power source to the motor. It istherefore unnecessary to remove the work from its operative relation tothe machine in order to stop the latter. This not only saves time incorrecting the difficulty but avoids the danger of serious damage to theunit.

A cable 21 (Fig. 1) serves to deliver the current from the lines EE ofFig. 4 to the circuit provided within the handle and the motor 1.

In Fig. 1 there is also shown the source of supply of thread for theneedle 7 and looper 8. This comprises a pair of cones or spools 22 and23 which are mounted on suitable rods carried by a support 24 mounted atthe top of the sewing machine in the manner more fully disclosed in saidpending application. Support '24 is preferably carried by a hood 25which is secured to the frame of the sewing machine '2 and which servesto cover and provide a guard over the needle lever 9 and otherope-rating parts of the machine which extend outwardly from the mainframe of the machine.

While theinvention has been described in considerable detail as appliedto a machine of the character disclosed in said pending application, itwill be understood that the invention is of broader application and maybe used in connection with other typesof sewing machine which may, ifdesired, produce other types of stitching than the double chain stitchproduced by the machine "disclosed. Other changes may be made in theconstruction and arrangement of the parts within the scope of theinvention as defined by the appended claims.

What is claimed is:

1. A sewing unit comprising a portable sewing machine having a handlefor carrying and guiding the same by the hand of the operator across thework to be stitched, an electric motor rigidly connected with saidmachine in constant driving relation thereto, means including a switchfor electrically connecting said motor with a power source, feeler meanscarried by said sewing machine in the path of the Work and arranged tobe operated by the work as the machine is moved into engagementtherewith by the hand of the operator, connections fromsaid feeler meansfor operating said switch to control the delivery of current from saidpower source {to said motor, a manually operable switch in series withwhich said machine is being guided for releasing said manually operableswitch by said hand of the operator.

2. A sewing unit comprising a portable sewing machine having a handlefor carrying and guiding the same by the hand of the operator across thework to be stitched, an electric motor rigidly connected with saidmachine in constant driving relation thereto, readily disconnectable'means for connecting said motor with said machine,

means including a switch mounted on said motor for electricallyconnecting said motor with a power source, said switch including anoperating element, feeler means carried by said sewing machine in thepath of the work and arranged to be operated by the work as the machineis moved into engagement therewith by the hand of the operator, andconnections from said feeler means for operating said switch to controlthe delivery of current from said power source to said motor, saidconnections from said feeler means comprising a member mounted formovement on said sewing machine and arranged to operate said switch byfree engagement with said operating element, said member being lightlyspring urged into inactive position, whereby said switch may be operatedupon the application of a relatively small force to said member throughsaid feeler means.

3. A sewing unit of the character set forth in claim 2 in which saidmember comprises a two-armed lever pivotally mounted on said sewingmachine and in which the arm extending from the pivot of said lever tosaid feeler means is substantially longer than the arm which extendsfrom said pivot to said switch.

4. A sewing unit of the character set forth in claim 2 in which saidsewing machine has a throat plate relative to which the work isadvanced, a shaft extending parallel with the line of stitch formationsubstantially in the plane of said throat plate, and a needle carryinglever rockable about the axis of said shaft and in which said membercomprises a two-armed lever pivotally connected with said shaft, one endof said lever carrying said feeler means and the other end thereofcooperating with said switch.

5. A sewing unit comprising a portable sewing machine having a handlefor carrying and guiding the same bythe hand of the operator across thework to be stitched,

an electric motor connected with said machine in constant drivingrelation thereto, means including a switch for electircally connectingsaid motor with a power source, said sewing machine having a throatplate relative to which said work is moved in the course of stitchformation, said throat plate having a pair of narrow elongated slotstherein parallel with the direction of stitch formation, a feeler membercooperating with the outer face of said throat plate, said feeler memberhaving a pair of elongated narrow ribs arranged to extend into saidslots in the throat plate and being normally in the path of the work,the arrangement being such that work moving relative to said throatplate in the direction of stitch formation will shift said feeler memberto carry said ribs out of said slots, means connecting said feelermember with said switch for operating the latter into closed positionupon such movement of the feeler member to electrically connect themotor with the power source, and spring means normally urging saidswitch into open posi- 'tion and through said connecting means urgingsaid ribs into said slots.

6. A sewing unit of the character set forth in claim 5 in which saidfeeler member has a portion of channel formation and is U-shaped incross-section, said ribs being formed by the sides of said channel.

7. A sewing unit comprising a portable sewing machine and an electricmotor rigidly connected with said machine in constant driving relationthereto, said unit having a handle for carrying and guiding the same bythe hand of the operator across the work to be stitched,

-a throat plate on said machine relative to which the work is advanced,a shaft in said machine extending parallel with the line of stitchformation substantially in the plane of said throat plate, a needlecarrying lever rockable about the axis of said shaft, means including aswitch mounted on said motor for electrically connecting said motor witha power source, feeler means carried by said sewing machine in the pathof the work and arranged to be operated by the work as the machine ismoved into engagement with the latter by the hand of the operator, andconnections from said feeler means to said switch for operating the sameto control the delivery of current from said power source to said motor,said connections from said feeler means comprising a two-armed leverpivotally connected with said shaft, one end of said lever carrying saidfeeler means and the other end thereof cooperating with said switch tooperate the same, said two-armed lever having a bridging extension inthe region of its pivotal connection with said shaft, said lever itselfand said bridging extension being pivotally connected with the oppositeends of said shaft, said lever being lightly spring urged into inactiveposition, whereby the application of a relatively small force to saidlever through said feeler means serves to operate said switch.

8. A sewing unit comprising a portable sewing machine and an electricmotor rigidly connected with said machine in constant driving relationthereto, said unit having a handle for carrying and guiding the same bythe hand of the operator across the work to be stitched, a throat plateon said machine relative to which the work is advanced, a shaft in saidmachine extending parallel with the line of stitch formationsubstantially in the plane of said throat plate, a needle carrying leverrockswitch mounted on said motor for electrically connecting said motorwith a power source, feeler means carried by said sewing machine in thepath of the work and arranged to be operated by the work as the machineis moved into engagement therewith by the hand of the operator,connections from said feeler means to said switch for operating the sameto control the delivery of current from said power source to said motor,said connections from said feeler means comprising a two-armed leverpivotally connected with said shaft, one end of said lever carrying saidfeeler means and the other end thereof cooperating with said switch tooperate the same, said lever being lightly spring urged into inactiveposition, whereby the application of a relatively small force to saidlever through said feeler means serves to operate said switch, and aspring urged plunger mounted in the end of said lever which cooperateswith said switch, said switch having a spring urged actuating elementwhich is engaged by said plunger.

References Cited in the file of this patent UNITED STATES PATENTS780,860 Brusseau Jan. 24, 1905 2,051,118 Weber et al Aug. 18, 19362,670,700 Kindseth Mar. 2, 1954 2,679,307 Koch May 25, 1954 FOREIGNPATENTS 1,128,988 France Jan. 14, 1957

